How to fetch related object using JDOQL named query?

Question

I'm using DataNucleus 2.0.5. And I need to run named JDOQL query to retrieve object with some of related entities.

Suppose I have

class Account{
     Set<Role> roles;
     //... other properties
}

Now I want to execute named query and retrieve account with roles. I need to do something very similar to join fetch in JPQL but using JDOQL named query.